This study will compare the hypolipidemic effects, influence on lipoprotein and cholesterol metabolism on gemfibrozil, simvastatin and atorvastatin in patients with type III hyperlipidemia. After a 4 week dietary baseline, patients will be treated in a random sequence with gemfibrozil, simvastatin or atorvastatin each for 8 weeks; efficacy, metabolic effects and safety will be evaluated on each regimen.